Methods of erasing data in nonvolatile memory devices and nonvolatile memory devices performing the same

ABSTRACT

A method of operating a nonvolatile memory device includes erasing data within a NAND string of memory cells within the memory device by applying a non-zero erase voltage to a source/drain terminal at a first end of the NAND string. This erase voltage is applied concurrently with establishing gate-induced drain leakage (GIDL) in a pair of selection transistors within the NAND string. This GIDL can occur by applying unequal and non-zero first and second voltages to respective first and second gate terminals of the pair of selection transistors. The selection transistors can be string selection transistors or ground selection transistors.

REFERENCE TO PRIORITY APPLICATION

This application is a continuation application of and claims priorityfrom U.S. patent application Ser. No. 16/205,334, filed Nov. 30, 2018,which claims priority under 35 USC § 119 to Korean Patent ApplicationNo. 10-2018-0028390, filed Mar. 12, 2018, the contents of which arehereby incorporated herein by reference in entirety.

BACKGROUND 1. Technical Field

Example embodiments relate generally to semiconductor devices and, moreparticularly, to methods of erasing data in nonvolatile memory devicesand nonvolatile memory devices performing the methods.

2. Description of the Related Art

Semiconductor memory devices can generally be divided into twocategories depending upon whether or not they retain stored data whendisconnected from a power supply. These categories include volatilememory devices, which lose stored data when disconnected from power, andnonvolatile memory devices, which retain stored data when disconnectedfrom power. Volatile memory devices may perform read and writeoperations at a high speed, while contents stored therein may be lost atpower-off. Nonvolatile memory devices may retain contents stored thereineven at power-off, which means they may be used to store data that mustbe retained regardless of whether they are powered. Recently,semiconductor memory devices having memory cells that are stacked“vertically” (i.e., in three dimensions (3D)) have been researched toimprove the capacity and integration density of the semiconductor memorydevices.

SUMMARY

At least one example embodiment of the present disclosure provides amethod of erasing data in a nonvolatile memory device, which containsmemory cells stacked in three dimensions to thereby improvecharacteristics and reliability of a data erase operations.

At least one example embodiment of the present disclosure providesnonvolatile memory devices performing methods of erasing data.

According to example embodiments, in a method of erasing data in anonvolatile memory device including one or more memory blocks, aplurality of memory cells are disposed in a vertical direction in eachmemory block. An erase voltage is applied to an erase source terminal ofa memory block. A first voltage is applied to a first selection lineamong a plurality of selection lines in the memory block. The firstvoltage is higher than the erase voltage. The first selection line isdisposed closest to the erase source terminal among the plurality ofselection lines and is used for selecting the memory block as an erasetarget block. A second voltage is applied to a second selection lineamong the plurality of selection lines. The second voltage is a non-zerovoltage that is lower than the erase voltage. The second selection lineis disposed farther from the erase source terminal than the firstselection line and is used for selecting the memory block as the erasetarget block.

According to example embodiments, in a method of erasing data in anonvolatile memory device including one or more memory blocks, aplurality of memory cells are disposed in a vertical direction in eachmemory block, and each memory block is divided into a first sub-blockand a second sub-block in the vertical direction. An erase voltage isapplied to an erase source terminal of a memory block. A first voltageis applied to a first selection line among a plurality of selectionlines in the memory block. The first voltage is higher than the erasevoltage. The first selection line is disposed closest to the erasesource terminal among the plurality of selection lines and is used forselecting the first sub-block as an erase target sub-block. The firstvoltage or a second voltage is applied to a second selection line amongthe plurality of selection lines based on a location relationshipbetween the erase source terminal and the first sub-block. The secondvoltage is lower than the erase voltage. The second selection line isdisposed farther from the erase source terminal than the first selectionline and is used for selecting the first sub-block as the erase targetsub-block.

According to additional example embodiments, a nonvolatile memory deviceincludes a memory block and a control circuit. The memory block includesa plurality of memory cells disposed in a vertical direction. Thecontrol circuit to applies an erase voltage to an erase source terminalof the memory block, and applies a first voltage to a first selectionline among a plurality of selection lines in the memory block. The firstvoltage is higher than the erase voltage. The first selection line isdisposed closest to the erase source terminal among the plurality ofselection lines and is used for selecting the memory block as an erasetarget block.

In a method of erasing data according to further embodiments and thenonvolatile memory device according to further embodiments, the firstvoltage higher than the erase voltage may be applied to the firstselection line disposed closest to the erase source terminal (e.g., thecommon source line contact and/or the bitline), the second voltage lowerthan the erase voltage may be applied to the second selection linedisposed farther from the erase source terminal than the first selectionline, and GIDL may occur between the first and second selection lines.Accordingly, the erase voltage applied to the erase source terminal maybe efficiently provided or delivered to the channel in the memory block,and the data erase operation based on the GIDL scheme may be efficientlyperformed. In addition, the location of occurring GIDL may be changedaccording to the number of times in which the data erase operation hasbeen performed, and thus reliability of the data erase operation may beimproved.

Further, when the memory block is implemented with the multi-stackedstructure, the location of occurring GIDL may be disposed in middle ofcell strings according to the location of the erase target sub-block.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative, non-limiting example embodiments will be more clearlyunderstood from the following detailed description taken in conjunctionwith the accompanying drawings.

FIG. 1 is a flow chart illustrating a method of erasing data in anonvolatile memory device according to example embodiments.

FIG. 2 is a block diagram illustrating a nonvolatile memory deviceaccording to example embodiments.

FIG. 3 is a perspective view illustrating an example of a memory blockthat is included in a memory cell array of the nonvolatile memory deviceof FIG. 2.

FIG. 4 is a circuit diagram illustrating an equivalent circuit of thememory block described with reference to FIG. 3.

FIG. 5 is a cross-sectional view of an example of a memory block that isincluded in a nonvolatile memory device according to exampleembodiments.

FIG. 6 is a flow chart illustrating an example of the method of FIG. 1.

FIG. 7 is a timing diagram for describing the method of FIG. 6.

FIG. 8 is a flow chart illustrating another example of the method ofFIG. 1.

FIG. 9 is a timing diagram for describing the method of FIG. 8.

FIG. 10 is a flow chart illustrating still another example of the methodof FIG. 1.

FIG. 11 is a timing diagram for describing the method of FIG. 10.

FIG. 12 is a cross-sectional view of an example of a memory block thatis included in a nonvolatile memory device according to exampleembodiments.

FIG. 13 is a flow chart illustrating a method of erasing data in anonvolatile memory device according to example embodiments.

FIG. 14 is a cross-sectional view of an example of a memory block thatis included in a nonvolatile memory device according to exampleembodiments.

FIGS. 15, 16, 17 and 18 are timing diagrams for describing the method ofFIG. 13.

FIG. 19 is a flow chart illustrating a method of erasing data in anonvolatile memory device according to example embodiments.

FIG. 20 is a cross-sectional view of an example of a memory block thatis included in a nonvolatile memory device according to exampleembodiments.

FIG. 21 is a cross-sectional view for describing a structure of thememory block of FIG. 20.

FIG. 22 is a flow chart illustrating an example of the method of FIG.19.

FIG. 23 is a timing diagram for describing the method of FIG. 22.

FIG. 24 is a flow chart illustrating another example of the method ofFIG. 19.

FIG. 25 is a timing diagram for describing the method of FIG. 24.

FIG. 26 is a block diagram illustrating a memory system according toexample embodiments.

FIG. 27 is a block diagram illustrating a storage device that includes anonvolatile memory device according to example embodiments.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Various example embodiments will be described more fully with referenceto the accompanying drawings, in which embodiments of the invention areshown. The present disclosure may, however, be embodied in manydifferent forms and should not be construed as limited to theembodiments set forth herein. Like reference numerals refer to likeelements throughout this application.

FIG. 1 is a flow chart illustrating a method of erasing data in anonvolatile memory device according to example embodiments of theinvention. Referring to FIG. 1, a method of erasing data according toexample embodiments is performed by a nonvolatile memory deviceincluding one or more memory blocks, and a plurality of memory cells aredisposed in a vertical direction within each memory block. In otherwords, each memory block includes a plurality of memory cells that arestacked in a vertical direction (i.e., substantially perpendicular to)relative to a surface of a substrate. Configurations of the nonvolatilememory device and the memory block will be described in detail withreference to FIGS. 2 through 4.

In the method of erasing data in the nonvolatile memory device accordingto example embodiments, an erase voltage is applied to an erase sourceterminal of the memory block (step S100). The erase source terminalrepresents a terminal that receives the erase voltage from an outside ofthe memory block (e.g., from a voltage generator). For example, theerase source terminal may include at least one of a common source linecontact that is formed or disposed in a lower portion of the memoryblock (e.g., in the substrate) and a bitline that is formed or disposedin an upper portion of the memory block (e.g., on the plurality ofmemory cells).

A first voltage that is higher than the erase voltage is applied to afirst selection line among a plurality of selection lines in the memoryblock (step S200). The first selection line represents a selection linethat is disposed closest to the erase source terminal among theplurality of selection lines and is used for selecting the memory blockas an erase target block. For example, the plurality of selection linesmay include a plurality of ground selection lines that are disposed inthe lower portion of the memory block and on the common source linecontact, and a plurality of string selection lines that are disposed inthe upper portion of the memory block and under the bitline.

A second voltage that is lower than the erase voltage is applied to asecond selection line among the plurality of selection lines (stepS300). The second selection line represents a selection line that isdisposed farther from the erase source terminal than the first selectionline and is used for selecting the memory block as the erase targetblock.

The first and second selection lines may be the same type of selectionlines. For example, when the first selection line is one of theplurality of ground selection lines, the second selection line may beanother of the plurality of ground selection lines. When the firstselection line is one of the plurality of string selection lines, thesecond selection line may be another of the plurality of stringselection lines. Thus, the memory block included in the nonvolatilememory device according to example embodiments may include two or moreground selection lines that are disposed in the vertical direction andtwo or more string selection lines that are disposed in the verticaldirection relative to the substrate.

The method of erasing data in the nonvolatile memory device according toexample embodiments may be performed based on a gate induced drainlowering or a gate induced drain leakage (GIDL) scheme. For example, thefirst voltage may be applied to the first selection line, the secondvoltage may be applied to the second selection line, and thus a GIDL mayoccur or may be generated between the first selection line and thesecond selection line, as will be described later.

In addition, the method of erasing data in the nonvolatile memory deviceaccording to example embodiments may be performed based on a command andan address for performing the data erase operation (e.g., in response toreceiving an erase command and an address for the erase target block).

FIG. 2 is a block diagram illustrating a nonvolatile memory deviceaccording to example embodiments of the invention (a/k/a/inventiveconcept). Referring to FIG. 2, a nonvolatile memory device 100 accordingto an embodiment of the invention includes, among other things, a memorycell array 110, a row decoder 120, a page buffer circuit 130, a datainput/output (I/O) circuit 140, a voltage generator 150 and a controlcircuit 160. The memory cell array 110 is connected to the row decoder120 via a plurality of string selection lines SSL, a plurality ofwordlines WL and a plurality of ground selection lines GSL. The memorycell array 110 is further connected to the page buffer circuit 130 via aplurality of bitlines BL. The memory cell array 110 may include aplurality of memory cells (e.g., a plurality of nonvolatile memorycells) that are connected to the plurality of wordlines WL and theplurality of bitlines BL. The memory cell array 110 may be divided intoa plurality of memory blocks BLK1, BLK2, . . . , BLKz, each of whichincludes memory cells.

In some example embodiments, as will be described with reference toFIGS. 3 and 4, the memory cell array 110 may be a three-dimensionalmemory cell array, which is formed on a substrate in a three-dimensionalstructure (or a vertical structure). In this example, the memory cellarray 110 may include a plurality of cell strings (e.g., a plurality ofvertical NAND strings) that are vertically oriented such that at leastone memory cell is located over another memory cell.

The control circuit 160 receives a command CMD and an address ADDR froma memory controller (e.g., a memory controller 600 in FIG. 26), andcontrol erasure, programming and read operations of the nonvolatilememory device 100 based on the command CMD and the address ADDR. Anerasure operation may include performing a sequence of erase loops, anda program operation may include performing a sequence of program loops.Each program loop may include a program operation and a programverification operation. Each erase loop may include an erase operationand an erase verification operation. The read operation may include anormal read operation and data recover read operation.

For example, the control circuit 160 may generate control signals CON,which are used for controlling the voltage generator 150, and maygenerate control signal PBC for controlling the page buffer circuit 130,based on the command CMD, and may generate a row address R_ADDR and acolumn address C_ADDR based on the address ADDR. The control circuit 160may provide the row address R_ADDR to the row decoder 120 and mayprovide the column address C_ADDR to the data I/O circuit 140.

In addition, the control circuit 160 operates to control the row decoder120, the page buffer circuit 130, the data I/O circuit 140 and thevoltage generator 150 based on the command CMD and the address ADDR, tothereby perform methods of erasing data in the nonvolatile memory device100 according to example embodiments of the invention (e.g., the methodof FIG. 1, etc.).

The row decoder 120 may be connected to the memory cell array 110 viathe plurality of string selection lines SSL, the plurality of wordlinesWL and the plurality of ground selection lines GSL. For example, in thedata erase/write/read operations, the row decoder 120 may determine atleast one of the plurality of wordlines WL as a selected wordline, andmay determine the rest or remainder of the plurality of wordlines WLother than the selected wordline as unselected wordlines, based on therow address R_ADDR. In addition, in the data erase/write/readoperations, the row decoder 120 may determine at least one of theplurality of string selection lines SSL as a selected string selectionline, and may determine the rest or remainder of the plurality of stringselection lines SSL other than the selected string selection line asunselected string selection lines, based on the row address R_ADDR.

Furthermore, in the data erase/write/read operations, the row decoder120 may determine at least one of the plurality of ground selectionlines GSL as a selected ground selection line, and may determine therest or remainder of the plurality of ground selection lines GSL otherthan the selected ground selection line as unselected ground selectionlines, based on the row address R_ADDR.

The voltage generator 150 may generate wordline voltages VWL that arerequired for an operation of the nonvolatile memory device 100 based ona power PWR and the control signals CON. The wordline voltages VWL maybe applied to the plurality of wordlines WL via the row decoder 120. Forexample, the wordline voltages VWL may include the first voltage and thesecond voltage described with reference to FIG. 1. In addition, thevoltage generator 150 may generate an erase voltage VERS that isrequired for the data erase operation based on the power PWR and thecontrol signals CON. The erase voltage VERS may be applied to the memorycell array 110 directly or via the bitline BL.

For example, during the erase operation, the voltage generator 150 mayapply the erase voltage VERS to a common source line contact and/or thebitline BL of a memory block (e.g., a selected memory block) and mayapply an erase permission voltage (e.g., a ground voltage) to allwordlines of the memory block or a portion of the wordlines via the rowdecoder 120. In addition, during the erase verification operation, thevoltage generator 150 may apply an erase verification voltagesimultaneously to all wordlines of the memory block or sequentially tothe wordlines one by one.

For example, during a program operation, the voltage generator 150 mayapply a program voltage to the selected wordline and may apply a programpass voltage to the unselected wordlines via the row decoder 120. Inaddition, during a program verification operation, the voltage generator150 may apply a program verification voltage to the selected wordlineand may apply a verification pass voltage to the unselected wordlinesvia the row decoder 120.

In addition, during a normal read operation, the voltage generator 150may apply a read voltage to the selected wordline and may apply a readpass voltage to the unselected wordlines via the row decoder 120. Duringa data recover read operation, the voltage generator 150 may apply theread voltage to a wordline adjacent to the selected wordline and mayapply a recover read voltage to the selected wordline via the rowdecoder 120.

The page buffer circuit 130 may be connected to the memory cell array110 via the plurality of bitlines BL. The page buffer circuit 130 mayinclude a plurality of page buffers. In some example embodiments of theinvention, each page buffer may be connected to one bitline. In otherexample embodiments, each page buffer may be connected to two or morebitlines.

The page buffer circuit 130 may store data DAT to be programmed into thememory cell array 110 or may read data DAT sensed from the memory cellarray 110. In other words, the page buffer circuit 130 may operate as awrite driver or a sensing amplifier according to an operation mode ofthe nonvolatile memory device 100.

The data I/O circuit 140 may be connected to the page buffer circuit 130via data lines DL. The data I/O circuit 140 may provide the data DATfrom an outside of the nonvolatile memory device 100 (e.g., from thememory controller 600 in FIG. 26) to the memory cell array 110 via thepage buffer circuit 130 or may provide the data DAT from the memory cellarray 110 to the outside of the nonvolatile memory device 100, based onthe column address C_ADDR.

FIG. 3 is a perspective view illustrating an example of a memory blockthat is included in a memory cell array of the nonvolatile memory deviceof FIG. 2. Referring to FIG. 3, a memory block BLKi includes NANDstrings which are formed on a substrate in a three-dimensional structure(or a vertical structure). The memory block BLKi includes structuresextending along first, second and third directions D1, D2 and D3. Asubstrate 111 is provided. For example, the substrate 111 may have awell of a first type (e.g., a first conductivity type) therein. Forexample, the substrate 111 may have a p-well formed by implanting agroup 3 element such as boron (B). In particular, the substrate 111 mayhave a pocket p-well provided within an n-well. In an embodiment, thesubstrate 111 has a p-type well (or a p-type pocket well). However, theconductive type of the substrate 111 is not limited to p-type.

A plurality of doping regions 311, 312, 313 and 314 extending along thefirst direction D1 are provided in/on the substrate 111. These pluralityof doping regions 311 to 314 may have a second type (e.g., a secondconductive type) different from the first type of the substrate 111. Inone embodiment of the invention, the first to fourth doping regions 311to 314 may have an n-type. However, the conductive type of the first tofourth doping regions 311 to 314 is not limited to n-type.

A plurality of insulation materials 112 extending along the seconddirection D2 are sequentially provided along the third direction D3 on aregion of the substrate 111 between the first and second doping regions311 and 312. For example, the plurality of insulation materials 112 areprovided along the second direction D3, being spaced by a specificdistance. For example, the insulation materials 112 may include aninsulation material such as an oxide layer.

A plurality of pillars 113 penetrating the insulation materials alongthe third direction D3 are sequentially disposed along the seconddirection D2 on a region of the substrate 111 between the first andsecond doping regions 311 and 312. For example, the plurality of pillars113 penetrate the insulation materials 112 to contact the substrate 111.In some example embodiments, each pillar 113 may include a plurality ofmaterials. For example, a channel layer 114 of each pillar 113 mayinclude a silicon material having a first conductivity type. Forexample, the channel layer 114 of each pillar 113 may include a siliconmaterial having the same conductivity type as the substrate 111. In oneembodiment of the invention, the channel layer 114 of each pillar 113includes p-type silicon. However, the channel layer 114 of each pillar113 is not limited to the p-type silicon.

An internal material 115 of each pillar 113 includes an insulationmaterial. For example, the internal material 115 of each pillar 113 mayinclude an insulation material such as a silicon oxide. In someexamples, the inner material 115 of each pillar 113 may include an airgap.

An insulation layer 116 is provided along the exposed surfaces of theinsulation materials 112, the pillars 113, and the substrate 111, on aregion between the first and second doping regions 311 and 312. Forexample, the insulation layer 116 provided on surfaces of the insulationmaterial 112 may be interposed between pillars 113 and a plurality ofstacked first conductive materials 211, 221, 231, 241, 251, 261, 271,281 and 291, as illustrated. In some examples, the insulation layer 116need not be provided between the first conductive materials 211 to 291corresponding to ground selection lines GSL (e.g., 211) and stringselection lines SSL (e.g., 291). In this example, the ground selectionlines GSL are the lowermost ones of the stack of first conductivematerials 211 to 291 and the string selection lines SSL are theuppermost ones of the stack of first conductive materials 211 to 291.

The plurality of first conductive materials 211 to 291 are provided onsurfaces of the insulation layer 116, in a region between the first andsecond doping regions 311 and 312. For example, the first conductivematerial 211 extending along the second direction D2 is provided betweenthe insulation material 112 adjacent to the substrate 111 and thesubstrate 111. In more detail, the first conductive material 211extending along the second direction D2 is provided between theinsulation layer 116 at the bottom of the insulation material 112adjacent to the substrate 111 and the substrate 111.

A first conductive material extending along the second direction D2 isprovided between the insulation layer 116 at the top of the specificinsulation material among the insulation materials 112 and theinsulation layer 116 at the bottom of a specific insulation materialamong the insulation materials 112. For example, a plurality of firstconductive materials 221 to 281 extending along the second direction D2are provided between the insulation materials 112 and it may beunderstood that the insulation layer 116 is provided between theinsulation materials 112 and the first conductive materials 221 to 281.The first conductive materials 211 to 291 may be formed of a conductivemetal, but in other embodiments of the invention the first conductivematerials 211 to 291 may include a conductive material such as apolysilicon.

The same structures as those on the first and second doping regions 311and 312 may be provided in a region between the second and third dopingregions 312 and 313. In the region between the second and third dopingregions 312 and 313, a plurality of insulation materials 112 areprovided, which extend along the second direction D2. And, a pluralityof pillars 113 are provided that are disposed sequentially along thesecond direction D2 and penetrate the plurality of insulation materials112 along the third direction D3. An insulation layer 116 is provided onthe exposed surfaces of the plurality of insulation materials 112 andthe plurality of pillars 113, and a plurality of first conductivematerials 211 to 291 extend along the second direction D2. Similarly,the same structures as those on the first and second doping regions 311and 312 may be provided in a region between the third and fourth dopingregions 313 and 314.

A plurality of drain regions 320 are provided on the plurality ofpillars 113, respectively. The drain regions 320 may include siliconmaterials doped with a second type. For example, the drain regions 320may include silicon materials doped with an n-type dopant. In oneembodiment of the invention, the drain regions 320 include n-typesilicon materials. However, the drain regions 320 are not limited ton-type silicon materials.

On the drain regions, a plurality of second conductive materials 331,332 and 333 are provided, which extend along the first direction D1. Thesecond conductive materials 331 to 333 are disposed along the seconddirection D2, being spaced by a specific distance. The second conductivematerials 331 to 333 are respectively connected to the drains 320 in acorresponding region. The drains 320 and the second conductive material333 extending along the first direction D1 may be connected through eachcontact plug. The second conductive materials 331 to 333 may includemetal materials. The second conductive materials 331 to 333 may includeconductive materials such as a polysilicon.

In an example of FIG. 3, the first conductive materials 211 to 291 maybe used to form the wordlines WL, the string selection lines SSL and theground selection lines GSL. For example, the first conductive materials221 to 281 may be used to form the wordlines WL, where conductivematerials belonging to the same layer may be interconnected. The secondconductive materials 331 to 333 may be used to form the bitlines BL. Thenumber of layers of the first conductive materials 211 to 291 may bechanged variously according to process and control techniques.

FIG. 4 is a circuit diagram (i.e., electrical schematic) illustrating anequivalent circuit of the memory block described with reference to FIG.3. The memory block BLKi of FIG. 4 may be formed on a substrate in athree-dimensional structure (or a vertical structure). For example, aplurality of cell strings or NAND strings included in the memory blockBLKi may be formed in a direction perpendicular to the substrate.Referring to FIG. 4, the memory block BLKi may include a plurality ofNAND strings NS11, NS12, NS13, NS21, NS22, NS23, NS31, NS32 and NS33connected between bitlines BL1, BL2 and BL3 and a common source lineCSL, as illustrated. Each of the NAND strings NS11 to NS33 may include aplurality of string selection transistors SST1 and SST2, a plurality ofmemory cells MC1, MC2, MC3, MC4, MC5 and MC6, and a plurality of groundselection transistors GST1 and GST2. For example, the bitlines BL1 toBL3 may correspond to the second conductive materials 331 to 333 in FIG.3, and the common source line CSL may be formed by interconnecting thefirst to fourth doping regions 311 to 314 in FIG. 3.

The plurality of string selection transistors SST1 and SST2 may beconnected to corresponding string selection lines SSL11, SSL12, SSL13,SSL21, SSL22 and SSL23, respectively. The plurality of memory cells MC1to MC6 may be connected to corresponding wordlines WL1, WL2, WL3, WL4,WL5 and WL6, respectively. The plurality of ground selection transistorsGST1 and GST2 may be connected to corresponding ground selection linesGSL11, GSL21, GSL22 and GSL23, respectively. The uppermost stringselection transistors SST2 may be connected to corresponding bitlinesBL1 to BL3, respectively, and the lowermost ground selection transistorsGST1 may be connected to the common source line CSL. In the example ofFIG. 4, some of the string selection transistors are connected to thesame bitline to connect corresponding NAND strings to the same bitlineupon appropriate selection via selection voltages applied to theappropriate sting selection lines and ground selection lines.

The cell strings connected in common to one bitline may form one column,and the cell strings connected to one string selection line may form onerow. For example, the cell strings NS11, NS21 and NS31 connected to thefirst bitline BL1 may correspond to a first column, and the cell stringsNS11, NS12 and NS13 connected to the first string selection line SSL1may form a first row.

Wordlines (e.g., WL1) having the same height may be commonly connected,the ground selection lines GSL11 may be commonly connected, and theground selection lines GSL21, GSL22 and GSL23 and the string selectionlines SSL11, SSL12, SSL13, SSL21, SSL22 and SSL23 may be separated.Memory cells located at the same semiconductor layer share a wordline.Cell strings in the same row share a string selection line. The commonsource line CSL is connected in common to all of the cell strings.

In FIG. 4, the memory block BLKi is illustrated as being connected tosix wordlines WL1 to WL6, three bitlines BL1 to BL3, the stringselection lines SSL11, SSL12, SSL13, SSL21, SSL22 and SSL23 with twostages, and the ground selection lines GSL11, GSL21, GSL22 and GSL23with two stages, and each of the NAND strings NS11 to NS33 isillustrated to include six memory cells MC1 to MC6. However, theinventive concepts are not limited to these illustrated embodiments. Insome example embodiments, each memory block in the memory cell array 100may be connected to any number of wordlines, bitlines, string selectionlines and ground selection lines, and each NAND string may include anynumber of memory cells. In addition, as will be described with referenceto FIG. 20, the memory block may be divided into a plurality ofsub-blocks that are disposed in the vertical direction (e.g., the thirddirection D3).

A three-dimensional vertical array structure may include vertical NANDstrings that are vertically oriented such that at least one memory cellis located over another memory cell. The at least one memory cell maycomprise a charge trap layer. The following patent documents, which arehereby incorporated by reference in their entirety, describe suitableconfigurations for a memory cell array including a 3D vertical arraystructure, in which the three-dimensional memory array is configured asa plurality of levels, with wordlines and/or bitlines shared betweenlevels: U.S. Pat. Nos. 7,679,133; 8,553,466; 8,654,587; 8,559,235; andUS Pat. Pub. No. 2011/0233648.

Although the memory cell array included in the nonvolatile memory deviceaccording to example embodiments is described based on a NAND flashmemory device, the nonvolatile memory device according to exampleembodiments may be any nonvolatile memory device, e.g., a phase randomaccess memory (PRAM), a resistive random access memory (RRAM), a nanofloating gate memory (NFGM), a polymer random access memory (PoRAM), amagnetic random access memory (MRAM), a ferroelectric random accessmemory (FRAM), a thyristor random access memory (TRAM), etc.

For convenience of illustration and description, memory cells areomitted in a memory block and the memory block includes only groundselection lines, wordlines, string selection lines and a bitline thatare stacked on one another in the vertical direction in followingfigures.

FIG. 5 is a cross-sectional view of an example of a memory block that isincluded in a nonvolatile memory device according to exampleembodiments. Referring to FIG. 5, a memory block may include a pluralityof memory cells disposed in the vertical direction, and may include alower (or lowermost) ground selection line GGSL, upper ground selectionlines GSLu (e.g., GSL0, GSL1, GSL2 and GSL3), a dummy wordline DWL0,wordlines WL (e.g., WL0, WL1, WL2, WL3, WL(N−4), WL(N−3), WL(N−2) andWL(N−1)), a dummy wordline DWL1, lower string selection lines SSLd(e.g., SSL0 d, SSL1 d, SSL2 d and SSL3 d), upper (or uppermost) stringselection lines SSLu (e.g., SSL0 u, SSL1 u, SSL2 u and SSL3 u), and abitline BL that are sequentially disposed on a substrate (or well) PPWin the vertical direction. The ground selection lines GGSL and GSL0 toGSL3 may be connected to ground selection transistors (e.g., the groundselection transistors GST1 and GST2 in FIG. 4), the dummy wordlines DWL0and DWL1 may be connected to dummy memory cells, the wordlines WL0 toWL(N−1) may be connected to the memory cells (e.g., the memory cells MC1to MC6 in FIG. 4), and the string selection lines SSL0 d to SSL3 d andSSL0 u to SSL3 u may be connected to string selection transistors (e.g.,the string selection transistors SST1 and SST2 in FIG. 4). In someexample embodiments, the dummy wordlines DWL0 and DWL1 may be omitted.

The memory block may include a common source line contact CSLC that isformed or disposed in a lower portion of the memory block (e.g., in thesubstrate PPW). In a plan view, the common source line contact CSLC maynot be entirely formed in the lower portion of the memory block. Forexample, as illustrated in FIG. 5, the common source line contact CSLCmay be disposed adjacent to the memory block and may not overlap thememory block in a plan view. For another example, as illustrated in FIG.3, the common source line contact CSLC may partially overlap the memoryblock in a plan view. For example, the substrate PPW may be a p-typesubstrate, and the common source line contact CSLC may be an N-typeregion, such as an N+ region.

FIG. 6 is a flow chart illustrating one example of the methodillustrated by the flow diagram of FIG. 1, and FIG. 7 is a timingdiagram for describing the method of FIG. 6. Referring to FIGS. 1, 5, 6and 7, in applying the erase voltage to the erase source terminal (stepS100), the erase voltage VERS may be applied to the common source linecontact CSLC (step S110). In applying the first voltage to the firstselection line (step S200), a first voltage V1 may be applied to theground selection line GGSL that is associated with the lowermost groundselection line (step S210). In applying the second voltage to the secondselection line (step S300), a second voltage V2 may be applied to theground selection lines GSLu that are disposed above the ground selectionline GGSL (step S310), as illustrated.

As illustrated in FIG. 7, a level of the first voltage V1 may be higherthan a level of the erase voltage VERS (e.g., V1=VERS+Vf), and a levelof the second voltage V2 may be positive, yet lower than the level ofthe erase voltage VERS (e.g., V2=VERS−Va).

A data erase operation illustrated in FIGS. 6 and 7 may be performedbased on the GIDL (i.e., gate-induced drain leakage) scheme. Forexample, the data erase operation in FIGS. 6 and 7 may be performed by abottom GIDL scheme in which the erase voltage VERS is provided to thememory block from the common source line contact CSLC, which can beformed in a lower portion of the memory block.

As illustrated in FIG. 5, in the memory block according to exampleembodiments, the common source line is not entirely formed in thesubstrate PPW, and the common source line contact CSLC is formed in aportion of the substrate PPW. In this example, when the erase voltageVERS is only applied to the common source line contact CSLC, thesubstrate PPW may be floated (e.g., may have a floating state), and theerase voltage VERS may not be provided to a channel in the memory block.

Thus, in the method of erasing data in the nonvolatile memory deviceaccording to example embodiments, the first voltage V1 higher than theerase voltage VERS may be applied to the lowermost ground selection lineGGSL that is disposed closest to the common source line contact CSLC tothereby deliver the erase voltage VERS to the upper ground selectionlines GSLu, and the second voltage V2 lower than the erase voltage VERSmay be applied to the upper ground selection lines GSLu to causegate-induced drain leakage (i.e., GIDL) between the lowermost groundselection line GGSL and the upper ground selection lines GSLu. As aresult, the erase voltage VERS applied to the common source line contactCSLC may be provided or delivered to the channel in the memory block. Inother words, GIDL may occur between the common source line and thelowermost ground selection line GGSL in a conventional nonvolatilememory device. However, GIDL may also occur between the lowermost groundselection line GGSL and the upper ground selection lines GSLu in thenonvolatile memory device according to example embodiments. An energyband may be bent by the GIDL, and charges (e.g., holes) for the dataerase operation may be generated and transferred (or moved).

In some example embodiments of the invention, the first voltage V1 maystart to apply to the lowermost ground selection line GGSL at an earlyfirst time point t1, the erase voltage VERS may start to apply to thecommon source line contact CSLC at a second time point t2 that is laterthan the first time point t1, and the second voltage V2 may start toapply to the upper ground selection lines GSLu at a third time point t3that is later than the second time point t2. The first voltage V1 may beapplied prior to applying the erase voltage VERS, and thus the dataerase operation may be efficiently performed.

In addition, while the erase voltage VERS is applied to the commonsource line contact CSLC, the same erase voltage VERS may be applied tothe bitline BL, and voltages V3 and V4 may be applied to the stringselection lines SSLd and SSLu, respectively. Levels of the voltages V3and V4 may be lower than the level of the erase voltage VERS,respectively (e.g., V3=VERS−Vc and V4=VERS−Vd). For example, the erasevoltage VERS may start to apply to the bitline BL at the second timepoint t2, the voltage V4 may start to apply to the uppermost stringselection lines SSLu at the third time point t3, and the voltage V3 maystart to apply to the lower string selection lines SSLd at a fourth timepoint t4, which is later than the third time point t3. A level increaseof the first voltage V1 may be finished at the fourth time point t4, andlevel increases of voltages other than the first voltage V1 may befinished at a fifth time point t5 that is later than the fourth timepoint t4. According to example embodiments, the erase voltage VERS maybe applied to all of the bitline BL and the string selection lines SSLdand SSLu as will be described with reference to FIG. 15, or all of thebitline BL and the string selection lines SSLd and SSLu may be floated.

Further, while the erase voltage VERS is applied to the common sourceline contact CSLC, an erase permission voltage VERSWL may be applied tothe wordlines WL to erase data stored in the memory cells connected tothe wordlines WL, and erase pass voltages VERSDWL0 and VERSDWL1 may beapplied to the dummy wordlines DWL0 and DWL1. The erase permissionvoltage VERSWL may represent a voltage that is used for erasing the datastored in the memory cells, and a level difference between a voltage inthe channel of the memory block and the erase permission voltage VERSWLmay be relatively low during the data erase operation. For example, whenthe erase voltage VERS of about 18V is applied to the channel of thememory block, the erase permission voltage VERSWL may be set to a groundvoltage (e.g., about 0V).

FIG. 8 is a flow chart illustrating another embodiment of the method ofFIG. 1, and FIG. 9 is a timing diagram for describing the method of FIG.8. Referring to FIGS. 1, 5, 8 and 9, when applying the erase voltage tothe erase source terminal (step S100), the erase voltage VERS may beapplied to the bitline BL (step S120). When applying the first voltageto the first selection line (step S200), the first voltage V1 may beapplied to the string selection lines SSLu that are the uppermost stringselection lines (step S220). When applying the second voltage to thesecond selection line (step S300), the second voltage V2 may be appliedto the string selection lines SSLd that are disposed lower than thestring selection lines SSLu (step S320).

A data erase operation illustrated in FIGS. 8 and 9 may be performedbased on the GIDL scheme. For example, the data erase operation in FIGS.8 and 9 may be performed by a top GIDL scheme in which the erase voltageVERS is provided to the memory block from the bitline BL that is formedin an upper portion of the memory block.

As with the bottom GIDL scheme, the first voltage V1 higher than theerase voltage VERS may be applied to the uppermost string selectionlines SSLu that are disposed closest to the bitline BL to deliver theerase voltage VERS to the lower string selection lines SSLd, and thesecond voltage V2 lower than the erase voltage VERS may be applied tothe lower string selection lines SSLd to thereby cause gate-induceddrain leakage (i.e., GIDL) between the uppermost string selection linesSSLu and the lower string selection lines SSLd. As a result, the erasevoltage VERS applied to the bitline BL may be provided or delivered tothe channel in the memory block. In other words, GIDL can occur betweenthe bitline BL and the uppermost string selection lines SSLu in anotherwise conventional nonvolatile memory device. However, GIDL may alsooccur between the uppermost string selection lines SSLu and the lowerstring selection lines SSLd in the nonvolatile memory device accordingto example embodiments of the invention.

In some example embodiments, as with the bottom GIDL scheme, the firstvoltage V1 may start to apply to the uppermost string selection linesSSLu at a first time point t1, the erase voltage VERS may start to applyto the bitline BL at a second time point t2 that is later than the firsttime point t1, and the second voltage V2 may start to apply to the lowerstring selection lines SSLd at a third time point t3 that is later thanthe second time point t2.

While the erase voltage VERS is applied to the bitline BL, operations ofdriving the common source line contact CSLC and the ground selectionlines GGSL and GSLu in FIG. 9 may be substantially the same asoperations of driving the bitline BL and the string selection lines SSLuand SSLd in FIG. 7, respectively, and operations of driving thewordlines WL and the dummy wordlines DWL0 and DWL1 in FIG. 9 may besubstantially the same as operations of driving the wordlines WL and thedummy wordlines DWL0 and DWL1 in FIG. 7, respectively.

FIG. 10 is a flow chart illustrating still another example of the methodof FIG. 1. FIG. 11 is a timing diagram for describing the method of FIG.10. Referring to FIGS. 1, 5, 10 and 11, in applying the erase voltage tothe erase source terminal (step S100), the erase voltage VERS may beapplied to the common source line contact CSLC (step S110), and theerase voltage VERS may be applied to the bitline BL simultaneously (stepS120). In applying the first voltage to the first selection line (stepS200), the first voltage V1 may be applied to the lowermost groundselection line GGSL (step S210), and the first voltage V1 may be appliedto the uppermost string selection lines SSLu simultaneously (step S220).In applying the second voltage to the second selection line (step S300),the second voltage V2 may be applied to the upper ground selection linesGSLu on the lowermost ground selection line GGSL (step S310), and thesecond voltage V2 may be applied to the lower string selection linesSSLd under the uppermost string selection lines SSLu simultaneously(step S320).

A data erase operation illustrated in FIGS. 8 and 9 may be performed bya mixed/hybrid GIDL scheme in which the bottom GIDL scheme describedwith reference to FIGS. 6 and 7 and the top GIDL scheme described withreference to FIGS. 8 and 9 are incorporated with each other. Steps S110,S210 and S310 in FIG. 10 may be substantially the same as steps S110,S210 and S310 in FIG. 6, respectively, and steps S120, S220 and S320 inFIG. 10 may be substantially the same as steps S120, S220 and S320 inFIG. 8, respectively. Operations of driving the common source linecontact CSLC, the ground selection lines GGSL and GSLu, the wordlines WLand the dummy wordlines DWL0 and DWL1 in FIG. 11 may be substantiallythe same as operations of driving the common source line contact CSLC,the ground selection lines GGSL and GSLu, the wordlines WL and the dummywordlines DWL0 and DWL1 in FIG. 7, respectively, and operations ofdriving the bitline BL and the string selection lines SSLu and SSLd inFIG. 11 may be substantially the same as operations of driving thebitline BL and the string selection lines SSLu and SSLd in FIG. 9,respectively.

FIG. 12 is a cross-sectional view of an example of a memory block thatis included in a nonvolatile memory device according to exampleembodiments. As shown by FIG. 12, a memory block may be implemented witha cell over periphery (COP) structure in which a peripheral circuit PERI(e.g., the row decoder 120, the page buffer circuit 130, the data I/Ocircuit 140, the voltage generator 150, the control circuit 160, etc.)is formed on a semiconductor substrate, and an insulation layer IL and amemory cell array including the memory block is stacked on theperipheral circuit PERI. The nonvolatile memory device may have arelatively small size by adopting the COP structure. The memory block ofFIG. 12 may be substantially the same as the memory block of FIG. 5,except that the memory block of FIG. 12 is implemented with the COPstructure.

When the memory block is implemented with the COP structure, a metallayer or a doped region may be formed to be directly connected to achannel of the memory block. When a data erase operation is performedfor a memory block having a COP structure, which is based on a bulkerase scheme in which the erase voltage VERS is directly applied to thesubstrate PPW, the erase voltage VERS is not sufficiently provided tothe channel of the memory block due to the metal layer or the dopedregion. Thus, in the memory block implemented with the COP structure,the GIDL scheme according to example embodiments may be efficient forthe data erase operation in comparison with the bulk erase scheme.

Although example embodiments are described with reference to FIGS. 5through 12 based on examples including ground selection lines with twostages and string selection lines with two stages in the verticaldirection, inventive concepts are not limited thereto. For example,example embodiments may be employed to various examples where a memoryblock includes ground selection lines with three or more stages andstring selection lines with three or more stages in the verticaldirection and GIDL occurs between any two adjacent ground selectionlines and/or between any two adjacent string selection lines.

FIG. 13 is a flow chart illustrating a method of erasing data in anonvolatile memory device according to example embodiments. Referring toFIG. 13, a method of erasing data according to example embodiments isperformed by a nonvolatile memory device including one or more memoryblocks, and a plurality of memory cells are disposed in a verticaldirection in each memory block. In addition, each memory block includesa plurality of selection lines that include a plurality of groundselection lines with three or more stages and a plurality of stringselection lines with three or more stages in the vertical direction.

In the method of erasing data in the nonvolatile memory device accordingto example embodiments, when a command and an address for performing adata erase operation are received, it is determined first whether afirst number representing the number of times in which the data eraseoperation has been performed is greater than a reference number (stepS500). Then, is the first number is smaller than or equal to thereference number (step S500: NO), a data erase scheme may be maintainedto perform the data erase operation (step S600). In other words, whenthe number of times in which the data erase operation has been performedis smaller than or equal to the reference number, the data eraseoperation may be performed based on an erase scheme that is initiallyset or determined. For example, an erase voltage is applied to an erasesource terminal of the memory block (step S100), a first voltage that ishigher than the erase voltage is applied to a first selection line amonga plurality of selection lines in the memory block (step S200), and asecond voltage that is lower than the erase voltage is applied to asecond selection line among the plurality of selection lines (stepS300).

Steps S100, S200 and S300 in FIG. 13 may be substantially the same assteps S100, S200 and S300 in FIG. 1, respectively, and may be performedbased on examples described with reference to FIGS. 5 through 11. Forexample, the data erase operation may be performed by establishing GIDLbetween the lowermost ground selection line GGSL and ground selectionlines disposed above the ground selection line GGSL and/or between theuppermost string selection lines SSLu and string selection linesdisposed lower than the string selection lines SSLu.

When the first number is greater than the reference number (step S500:YES), (e.g., when the number of times in which the data erase operationhas been performed is greater than the reference number), the data erasescheme may be changed to perform the data erase operation (step S700).For example, the erase voltage is applied to the erase source terminalof the memory block (step S100 a), the first voltage that is higher thanthe erase voltage is applied to the first selection line and the secondselection line (step S200 a), and the second voltage that is lower thanthe erase voltage is applied to a third selection line among theplurality of selection lines (step S300 a). The third selection linerepresents a selection line that is disposed farther from the erasesource terminal than the second selection line and is used for selectingthe memory block as the erase target block. In other words, a locationof the GIDL in step S700 may be different from a location of the GIDL instep S600.

FIG. 14 is a cross-sectional view of an example of a memory block thatis included in a nonvolatile memory device according to exampleembodiments. FIGS. 15, 16, 17 and 18 are timing diagrams for describingthe method of FIG. 13.

Referring to FIG. 14, a memory block may be substantially the same asthe memory block of FIG. 5, except that the memory block of FIG. 14includes ground selection lines with three stages and string selectionlines with three stages in the vertical direction. The ground selectionlines may include a lower (or lowermost) ground selection line GGSL,middle ground selection lines GSLm (e.g., GSL0 m, GSL1 m, GSL2 m andGSL3 m), and upper ground selection lines GSLu (e.g., GSL0 u, GSL1 u,GSL2 u and GSL3 u). The string selection lines may include lower stringselection lines SSLd (e.g., SSL0 d, SSL1 d, SSL2 d and SSL3 d), middlestring selection lines SSLm (e.g., SSL0 m, SSL1 m, SSL2 m and SSL3 m),and upper (or uppermost) string selection lines SSLu (e.g., SSL0 u, SSL1u, SSL2 u and SSL3 u).

Referring to FIGS. 13, 14, 15 and 16, the data erase operation may beperformed based on the bottom GIDL scheme. Thus, when the first numberis smaller than or equal to the reference number (step S500: NO), thedata erase operation may be performed such that GIDL occurs between thelowermost ground selection line GGSL and the middle ground selectionlines GSLm, as illustrated in FIG. 15.

Operations of driving the common source line contact CSLC and the groundselection line GGSL in FIG. 15 may be substantially the same asoperations of driving the common source line contact CSLC and the groundselection line GGSL in FIG. 7, respectively, and operations of drivingthe ground selection lines GSLm and GSLu in FIG. 15 may be substantiallythe same as an operation of driving the ground selection lines GSLu inFIG. 7.

When the first number is greater than the reference number (step S500:YES), the data erase operation may be performed such that GIDL occursbetween the middle ground selection lines GSLm and the upper groundselection lines GSLu, as illustrated in FIG. 16. Operations of drivingthe common source line contact CSLC and the ground selection line GSLuin FIG. 16 may be substantially the same as operations of driving thecommon source line contact CSLC and the ground selection line GSLu inFIG. 7, respectively, and operations of driving the ground selectionlines GGSL and GSLm in FIG. 16 may be substantially the same as anoperation of driving the ground selection line GGSL in FIG. 7.

Referring to FIGS. 13, 14, 17 and 18, the data erase operation may beperformed based on the top GIDL scheme. When the first number is smallerthan or equal to the reference number (step S500: NO), the data eraseoperation may be performed such that GIDL occurs between the uppermoststring selection lines SSLu and the middle string selection lines SSLm,as illustrated in FIG. 17. Operations of driving the bitline BL and thestring selection lines SSLu in FIG. 17 may be substantially the same asoperations of driving the bitline BL and the string selection lines SSLuin FIG. 9, respectively, and operations of driving the string selectionlines SSLm and SSLd in FIG. 17 may be substantially the same as anoperation of driving the string selection lines SSLd in FIG. 9.

When the first number is greater than the reference number (step S500:YES), the data erase operation may be performed such that GIDL occursbetween the middle string selection lines SSLm and the lower stringselection lines SSLd, as illustrated in FIG. 18. Operations of drivingthe bitline BL and the string selection lines SSLd in FIG. 18 may besubstantially the same as operations of driving the bitline BL and thestring selection lines SSLd in FIG. 9, respectively, and operations ofdriving the string selection lines SSLu and SSLm in FIG. 18 may besubstantially the same as an operation of driving the string selectionline SSLu in FIG. 9.

The erase voltage VERS may be applied to all of the bitline BL and thestring selection lines SSLu, SSLm and SSLd in FIGS. 15 and 16, and theerase voltage VERS may be applied to all of the common source linecontact CSLC and the ground selection lines GGSL, GSLm and GSLu in FIGS.17 and 18. Operations of driving the wordlines WL and the dummywordlines DWL0 and DWL1 in FIGS. 15 through 18 may be substantially thesame as operations of driving the wordlines WL and the dummy wordlinesDWL0 and DWL1 in FIG. 7, respectively.

Although example embodiments are described with reference to FIGS. 13through 18 based on examples including ground selection lines with threestages and string selection lines with three stages in the verticaldirection, inventive concepts are not limited thereto. For example,example embodiments may be employed to various examples where a memoryblock includes including ground selection lines with four or more stagesand string selection lines with four or more stages in the verticaldirection and/or a location of occurring GIDL is changed more than twotimes. Although not illustrated in FIGS. 15 through 18, exampleembodiments may be employed to an example where the data erase operationis performed by the mixed GIDL scheme in which the bottom GIDL schemeand the top GIDL scheme are incorporated with each other.

In the method of erasing data in the nonvolatile memory device accordingto example embodiments, a location of occurring GIDL may be changedaccording to the number of times in which the data erase operation hasbeen performed, and thus reliability of the data erase operation may beimproved.

FIG. 19 is a flow chart illustrating a method of erasing data in anonvolatile memory device according to example embodiments. As shown byFIG. 19, a method of erasing data according to example embodiments isperformed by a nonvolatile memory device including one or more memoryblocks, a plurality of memory cells are disposed in a vertical directionin each memory block, and each memory block is divided into a pluralityof sub-blocks (e.g., a first sub-block and a second sub-block) in thevertical direction. In other words, a data erase operation may beperformed by units of a sub-block, and not by units of a memory block.

In these method of erasing data in the nonvolatile memory deviceaccording to example embodiments, an erase voltage is applied to anerase source terminal of the memory block (step S1100). The erase sourceterminal represents a terminal that receives the erase voltage from anoutside of the memory block (e.g., from a voltage generator). Step S1100in FIG. 19 may be substantially the same as step S100 in FIG. 1.

A first voltage that is higher than the erase voltage is applied to afirst selection line among a plurality of selection lines in the memoryblock (step S1200). The first selection line represents a selection linethat is disposed closest to the erase source terminal among theplurality of selection lines and is used for selecting the firstsub-block as an erase target sub-block.

The first voltage that is higher than the erase voltage or a secondvoltage that is lower than the erase voltage is applied to a secondselection line among the plurality of selection lines based on alocation relationship between the erase source terminal and the firstsub-block (step S1300). The second selection line represents a selectionline that is disposed farther from the erase source terminal than thefirst selection line and is used for selecting the first sub-block asthe erase target sub-block. The first and second selection lines may bethe same type of selection lines. The method of erasing data in thenonvolatile memory device according to example embodiments may beperformed based on the GIDL scheme and may be performed based on acommand and an address for performing the data erase operation.

FIG. 20 is a cross-sectional view of an example of a memory block thatis included in a nonvolatile memory device according to exampleembodiments.

Referring to FIG. 20, a memory block may be substantially the same asthe memory block of FIG. 5, except that the memory block of FIG. 20 isdivided into two sub-blocks. Wordlines in FIG. 20 may be divided intolower wordlines WLd (e.g., WL0, WL1, WL(N−1)) and upper wordlines WLu(e.g., WLN, WL(N+1), WL(2N−1)) by dummy wordlines DWLd and DWLu. Memorycells connected to the upper wordlines WLu may form an upper sub-blockor a first sub-blocks SBu, and memory cells connected to the lowerwordlines WLd may form a lower sub-block or a second sub-blocks SBd.

FIG. 21 is a cross-sectional view for describing a structure of thememory block of FIG. 20. Referring to FIG. 21, a channel hole of eachcell string may include a first sub channel hole 410 and a second subchannel hole 420. A channel hole may be referred to as a pillar. Thefirst sub channel hole 410 may include a channel layer 411, an innermaterial 412 and an insulation layer 413. The second sub channel hole420 may include a channel layer 421, an inner material 422 and aninsulation layer 423. The channel layer 411 of the first channel hole410 may be connected to the channel layer 421 of the second sub channelhole 420 through a p-type silicon pad SIP. The sub channel holes 410 and420 may be formed using a stopper line GTL5 having an appropriate etchrate. For example, the stopper line GTL5 may be formed of polysiliconand the other wordlines GTL1, GTL2, GTL3, GTL4, GTL6, GTL7 and GTL8 maybe formed of metal such as tungsten to implement the appropriate etchrate.

The dummy wordlines DWLd and DWLu between the sub-blocks SBu and SBd inFIG. 20 may correspond to the stopper layer GTL5 that is used to formthe plurality of sub channel holes. The cells in the stopper layer GTL5may be improper for storing data.

As described with reference to FIGS. 20 and 21, a structure in which onechannel hole is formed using a plurality of sub channel holes may bereferred to as a multi-stacked string structure or simply amulti-stacked structure. The multi-stacked structure may be adopted whenit is difficult to form one channel hole at once because of increasingthe number of stacked wordlines. When the memory block is implementedwith the multi-stacked structure, a metal layer or a doped region may beformed to be directly connected to a channel of the memory block. Thus,in the memory block implemented with the multi-stacked structure, theGIDL scheme according to example embodiments may be efficient for thedata erase operation in comparison with the bulk erase scheme.

FIG. 22 is a flow chart illustrating an example of the method of FIG.19. FIG. 23 is a timing diagram for describing the method of FIG. 22.Referring to FIGS. 19, 20, 22 and 23, the data erase operation may beperformed based on the bottom GIDL scheme, and the first sub-block SBurepresenting the erase target sub-block may be disposed upper than thesecond sub-block SBd.

In applying the erase voltage to the erase source terminal (step S1100),the erase voltage VERS may be applied to the common source line contactCSLC (step S1110). In applying the first voltage to the first selectionline (step S1200), the first voltage V1 may be applied to the lowermostground selection line GGSL (step S1210). In applying the first voltageor the second voltage to the second selection line (step S1300), thefirst voltage V1 may be applied to the ground selection lines GSLu thatare disposed upper than the ground selection line GGSL (step S1310).Additionally, the first voltage V1 may be applied to the wordlines WLdconnected to the second sub-block SBd and the dummy wordline DWLddisposed closer to the second sub-block SBd than the dummy wordline DWLu(step S1410), and the second voltage V2 may be applied to the dummywordline DWLu disposed closer to the first sub-block SBu than the dummywordline DWLd (step S1420).

In the method of erasing data in the nonvolatile memory device accordingto example embodiments, the first voltage V1 higher than the erasevoltage VERS may be applied to the ground selection lines GGSL and GSLu,the wordlines WLd and the dummy wordline DWLd to deliver the erasevoltage VERS to the dummy wordline DWLu, and the second voltage V2 lowerthan the erase voltage VERS may be applied to the dummy wordline DWLu tooccur GIDL between the dummy wordline DWLd and the dummy wordline DWLu.As a result, the erase voltage VERS applied to the common source linecontact CSLC may be provided or delivered to a channel in the firstsub-block SBu. In other words, GIDL may occur between the dummy wordlineDWLd and the dummy wordline DWLu.

Operations of driving the bitlines BL, the string selection lines SSLuand SSLd and the wordlines WLu in FIG. 23 may be substantially the sameas operation of driving the bitlines BL, the string selection lines SSLuand SSLd and the wordlines WL in FIG. 7, respectively.

FIG. 24 is a flow chart illustrating another example of the method ofFIG. 19. FIG. 25 is a timing diagram for describing the method of FIG.24. Referring to FIGS. 19, 20, 24 and 25, the data erase operation maybe performed based on the top GIDL scheme, and the first sub-block SBurepresenting the erase target sub-block may be disposed upper than thesecond sub-block SBd.

In applying the erase voltage to the erase source terminal (step S1100),the erase voltage VERS may be applied to the bitline BL (step S1120). Inapplying the first voltage to the first selection line (step S1200), thefirst voltage V1 may be applied to the uppermost string selection linesSSLu (step S1220). In applying the first voltage or the second voltageto the second selection line (step S1300), the second voltage V2 may beapplied to the string selection lines SSLd that are disposed lower thanthe string selection lines SSLu (step S1320).

Steps S1120, S1220 and S1320 in FIG. 24 may be substantially the same assteps S120, S220 and S320 in FIG. 8, respectively, and an operation ofFIG. 25 may be substantially the same as an operation of FIG. 9. Inother words, GIDL may occur between the uppermost string selection linesSSLu and the lower string selection lines SSLd.

When the second sub-block SBd is selected as the erase target sub-block,a data erase operation may be similar to the data erase operationdescribed with reference to FIGS. 22 through 25. For example, in the topGIDL scheme, the erase voltage VERS may be applied to the bitline BL,the first voltage V1 may be applied to the string selection lines SSLuand SSLd, the wordlines WLu and the dummy wordline DWLu, the secondvoltage V2 may be applied to the dummy wordline DWLd, and thus GIDL mayoccur between the dummy wordline DWLu and the dummy wordline DWLd. Inthe bottom GIDL scheme, the data erase operation may be substantiallythe same as an operation of FIG. 7.

Although example embodiments are described with reference to FIGS. 20through 25 based on examples including ground selection lines with twostages, string selection lines with two stages and two sub-blocks,inventive concepts are not limited thereto. For example, exampleembodiments may be employed to various examples where a memory blockincludes ground selection lines with three or more stages and stringselection lines with three or more stages and/or includes three or moresub-blocks. In addition, example embodiments may be employed to anexample where the data erase operation is performed by the mixed GIDLscheme and/or an example where a location of occurring GIDL is changedaccording to the number of times in which the data erase operation hasbeen performed.

As will be appreciated by those skilled in the art, the presentdisclosure may be embodied as a system, method, computer programproduct, and/or a computer program product embodied in one or morecomputer readable medium(s) having computer readable program codeembodied thereon. The computer readable program code may be provided toa processor of a general purpose computer, special purpose computer, orother programmable data processing apparatus. The computer readablemedium may be a computer readable signal medium or a computer readablestorage medium. The computer readable storage medium may be any tangiblemedium that can contain, or store a program for use by or in connectionwith an instruction execution system, apparatus, or device. For example,the computer readable medium may be a non-transitory computer readablemedium.

FIG. 26 is a block diagram illustrating a memory system according toexample embodiments. Referring to FIG. 26, a memory system 500 includesa memory controller 600 and at least one nonvolatile memory device 700.The nonvolatile memory device 700 may correspond to the nonvolatilememory device according to example embodiments, and may perform dataerase, program (or write) and/or read operations under control of thememory controller 600. The nonvolatile memory device 700 may receive acommand CMD and an address ADDR through I/O lines from the memorycontroller 600 for performing such operations, and may exchange data DATwith the memory controller 600 for performing such program or readoperation. In addition, the nonvolatile memory device 700 may receive acontrol signal CTRL through a control line from the memory controller600. In addition, the nonvolatile memory device 700 receives a power PWRthrough a power line from the memory controller 600.

FIG. 27 is a block diagram illustrating a storage device that includes anonvolatile memory device according to example embodiments. Referring toFIG. 27, a storage device 1000 may include a plurality of nonvolatilememory devices 1100 and a controller 1200. For example, the storagedevice 1000 may be any storage device such as an embedded multimediacard (eMMC), a universal flash storage (UFS), a solid state disc orsolid state drive (SSD), etc. The controller 1200 may be connected tothe nonvolatile memory devices 1100 via a plurality of channels CH1,CH2, CH3 . . . CHi. The controller 1200 may include one or moreprocessors 1210, a buffer memory 1220, an error correction code (ECC)circuit 1230, a host interface 1250 and a nonvolatile memory interface1260.

The buffer memory 1220 may store data used to drive the controller 1200.The ECC circuit 1230 may calculate error correction code values of datato be programmed during a program operation, and may correct an error ofread data using an error correction code value during a read operation.In a data recovery operation, the ECC circuit 1230 may correct an errorof data recovered from the nonvolatile memory devices 1100. The hostinterface 1250 may provide an interface with an external device. Thenonvolatile memory interface 1260 may provide an interface with thenonvolatile memory devices 1100. Each of the nonvolatile memory devices1100 may correspond to the nonvolatile memory device according toexample embodiments, and may be optionally supplied with an externalhigh voltage VPP.

The inventive concept may be applied to various devices and systems thatinclude an nonvolatile memory device. For example, the inventive conceptmay be applied to systems such as a mobile phone, a smart phone, atablet computer, a laptop computer, a personal digital assistant (PDA),a portable multimedia player (PMP), a digital camera, a portable gameconsole, a music player, a camcorder, a video player, a navigationdevice, a wearable device, an internet of things (IoT) device, aninternet of everything (IoE) device, an e-book reader, a virtual reality(VR) device, an augmented reality (AR) device, a robotic device, etc.

The foregoing is illustrative of example embodiments and is not to beconstrued as limiting thereof. Although a few example embodiments havebeen described, those skilled in the art will readily appreciate thatmany modifications are possible in the example embodiments withoutmaterially departing from the novel teachings and advantages of thepresent disclosure. Accordingly, all such modifications are intended tobe included within the scope of the present disclosure as defined in theclaims. Therefore, it is to be understood that the foregoing isillustrative of various example embodiments and is not to be construedas limited to the specific example embodiments disclosed, and thatmodifications to the disclosed example embodiments, as well as otherexample embodiments, are intended to be included within the scope of theappended claims.

What is claimed is:
 1. A nonvolatile memory device comprising: a memoryblock including a plurality of memory cells disposed in a verticaldirection; and a control circuit configured to apply an erase voltage toan erase source terminal of the memory block, and configured to apply afirst voltage to a first selection line among a plurality of selectionlines in the memory block, the first voltage being higher than the erasevoltage, the first selection line being disposed closest to the erasesource terminal among the plurality of selection lines and being usedfor selecting the memory block as an erase target block.
 2. Thenonvolatile memory device of claim 1, wherein: the control circuit isconfigured to apply a second voltage to a second selection line amongthe plurality of selection lines, the second voltage is lower than theerase voltage, and the second selection line is disposed farther fromthe erase source terminal than the first selection line and is used forselecting the memory block as the erase target block.
 3. The nonvolatilememory device of claim 1, wherein: the memory block is divided into afirst sub-block and a second sub-block in the vertical direction, thecontrol circuit is configured to apply the first voltage or a secondvoltage to a second selection line among the plurality of selectionlines based on a location relationship between the erase source terminaland the first sub-block, the second voltage is lower than the erasevoltage, and the second selection line is disposed farther from theerase source terminal than the first selection line and is used forselecting the first sub-block as an erase target sub-block.
 4. A methodof erasing data in a memory block within the nonvolatile memory device,comprising: applying a non-zero erase voltage to a drain terminal afirst string selection transistor within a vertical NAND string ofmemory cells comprising at least two string selection transistors;applying a first voltage having a magnitude greater than the erasevoltage to a first string selection line associated with the firststring selection transistor; and applying a non-zero second voltagehaving a magnitude less than the erase voltage to a second stringselection line associated with a second string selection transistorbelow the first string selection transistor within the vertical NANDstring of memory cells.
 5. The method of claim 4, wherein the source ofthe first string selection transistor is electrically connected to adrain of the second string selection transistor; wherein said applyingthe first voltage commences prior to said applying the non-zero erasevoltage; and wherein said applying the non-zero erase voltage commencesprior to said applying a non-zero second voltage.
 6. A method ofoperating a nonvolatile memory device, comprising: erasing data within aNAND string of memory cells within the nonvolatile memory device byapplying a non-zero erase voltage to a source/drain terminal at a firstend of the NAND string concurrently with establishing gate-induced drainleakage (GIDL) in a pair of selection transistors within the NANDstring, by applying unequal and non-zero first and second voltages torespective first and second gate terminals of the pair of selectiontransistors.
 7. The method of claim 6, wherein the pair of selectiontransistors are a pair of string selection transistors or a pair ofground selection transistors.
 8. The method of claim 7, wherein a sourceof a first one of the pair of selection transistors is electricallyconnected to a drain of a second one of the pair of selectiontransistors.
 9. The method of claim 6, wherein the first voltage has amagnitude greater than the erase voltage and the second voltage has amagnitude less than the erase voltage.